Nonwoven fabrics are used in a variety of applications such as garments, disposable medical products, diapers, personal hygiene products, among others. New products being developed for these applications have demanding performance requirements, including comfort, conformability to the body, freedom of body movement, good softness and drape, adequate tensile strength and durability, and resistance to surface abrasion, pilling or fuzzing. Accordingly, the nonwoven fabrics which are used in these types of products must be engineered to meet these performance requirements.
Traditionally, such nonwoven fabrics are prepared from thermoplastic polymers, such as polyester, polystyrene, polyethylene, and polypropylene. These polymers are generally very stable and can remain in the environment for a long time. Recently, however, there has been a trend to develop articles and products that are considered environmentally friendly and sustainable. As part of this trend, there has been a desire to produce ecologically friendly products comprised of increased sustainable content in order to reduce the content of petroleum based materials.
Polylactic acid or polylactide-based polymers (PLA) provide a cost-effective path to sustainable content spunbond nonwovens that can be readily converted into consumer products. To fully capture the cost-effective benefits of PLA-based consumer products, PLA must be convertible into nonwovens and then into the final consumer product at very high speeds with minimal waste. However, it is difficult to combine the steps of spinning, web formation, and bonding at the very high speeds needed for the economically attractive production of spunbond PLA with desired fabric properties.
To address this need, nonwovens have been developed having a sheath/core bicomponent structure in which the PLA is present in the core, and a synthetic polymer, such as polypropylene, is in the sheath. Such nonwovens are described in U.S. Pat. No. 6,506,873. The presence of the synthetic polymer in the sheath provides the necessary properties for commercial production of nonwovens comprising PLA at high speeds.
Accordingly, there still exists a need for systems and processes for static protection during the processing of PLA.